Bold new hybrid planned: Yamaha design has petrol motor to extend electric battery range

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Hybrid cars are rapidly becoming the norm as a stepping stone to full electric power and there’s a growing suggestion that bikes might take the same route.

In 2030 it will become illegal to sell new cars in the UK that are purely fossil-fuelled, with sales of combustion-engined machines due to end just five years after that. Even without specific legislation, the pressure for bikes to follow suit will only increase as we get nearer that date.

Kawasaki have already made commitments to a rapid growth in their battery-powered line-up, with plans to launch large numbers of hybrid and pure-electric models, and it now looks like Yamaha is also reconsidering the idea of hybrid motorcycles.

Yamaha was a pioneer in the area. Back in 2005 it showed two hybrid-powered concepts; the Gen-Ryu combined an R6 engine with an electric motor in a low-slung tourer, while the HV-01 was a more conventional scooter using the same idea.

Yamaha hybrid motorcycle patent drawing

Yamaha’s Luxair hybrid concept followed in 2007, and in 2009 the HV-X demonstrated a near-production hybrid system with a 250cc single and a 20hp electric motor working together in a maxi-scooter – appearing just as the global financial crisis crushed R&D budgets. Now, the firm’s interest in the idea has been revived.

The old Yamahas were parallel hybrids, with the petrol engine and electric motor both driving the rear wheel either on their own or in tandem. But Yamaha’s new designs feature a hybrid set-up where the drive system is purely electric but with a small petrol engine used as a range-extending generator to recharge the batteries.

A patent for such a bike emerged in 2020 and now further documents showing three hybrid designs have been published.

The smallest is a 125cc-size scooter, with the petrol engine/generator unit low in the frame, a battery under the seat and an electric motor in the swingarm. With no need to drive the rear wheel, the petrol-powered generator section is bolted to elastic mounts so vibrations don’t reach the frame or rider.

Yamaha hybrid scooter patent drawing

The single-cylinder engines would lack the power and torque to give usable performance on their own, but by running at their most efficient rpms they can constantly trickle-charge the battery.

Combustion engines are more efficient when warm; electric ones are better kept cool. Yamaha’s designs show multiple possible variations on radiator set-ups to achieve this goal.

Next is a maxi-scooter design with a TMAX-style chassis, with the petrol engine and generator sitting ahead of the electric motor between the rider’s legs and a conventional chain or belt drive to the rear wheel.

Finally, there’s a motorcycle that positions its small petrol engine high up, just behind the steering head, with a large electric powertrain filling the space where you’d normally find the engine and transmission.

With a fast-growing focus on alternative powertrains these patents are likely to be the tip of the iceberg, and with Kawasaki expected to officially launch its first hybrid later this year a Yamaha might not be far behind.

Ben Purvis

By Ben Purvis